docs: def observe(self, key, master_only=False):
          """Return storage information for a key.
  
          It returns a :class:`.ValueResult` object with the ``value``
          field set to a list of :class:`~.ObserveInfo` objects. Each
          element in the list responds to the storage status for the key
          on the given node. The length of the list (and thus the number
          of :class:`~.ObserveInfo` objects) are equal to the number of
          online replicas plus the master for the given key.
  
          :param string key: The key to inspect
          :param bool master_only: Whether to only retrieve information
              from the master node.
  
          .. seealso:: :ref:`observe_info`
          """
          return _Base.observe(self, key, master_only=master_only)